Point-of-Use Disinfection of Household Drinking Water with Copper/Zinc Ions and Oxide Nanoparticles: a Proof-of-Concept Lab Study

摘要

Water in households of the developing world is often microbially unsafe and the cause ofrnwaterborne disease. Therefore, simple, effective and convenient treatment methods arernneeded to disinfect such household water. Disinfecting water with antimicrobial metals asrnions or nanoparticles has been inadequately studied for this application. This researchrnquantified the disinfecting efficacy of low (0.2 mg/L) and high (2 mg/l) doses ofrncombinations of ionic copper and zinc and copper and zinc oxide nanoparticles in modelrnbuffered water that are considered safe for consumption. Kinetics of disinfection werernquantified for three test microorganisms: Bacillus cereus spores, Escherichia coli, and MS-2rncoliphage in pH 7.3, 0.04M HEPES-buffered water with and without 10 mg/L added naturalrnaquatic organic matter (NOM); concentrations of culturable microorganisms were assayed atrn0, 20, 60, 180, and 360 minutes of contact time. Disinfection conditions that could meet thernWorld Health Organization (WHO) “protective” performance guideline levels of 2 log10rnbacteria and parasite reduction (for E. coli and spores of B. cereus, respectively) and 3 log10rnvirus reduction (for MS-2 coliphage) within 12 hours were investigated for kinetic modeling.rnSeveral test conditions of metal form (ion or nanoparticle oxide) and concentrations werernefficacious against virus, bacteria and protozoan parasite surrogates within the 12 hourrncontact time specified. Both copper and zinc ions and nanoparticles oxides were effective inrnachieving microbial reduction targets in buffered test water lacking added NOM. None of therntest conditions were effective in meeting microbial reduction targets in test water lackingrnadded NOM. Additional studies are needed to better document the effect of NOM and otherrnwater quality parameters (such as turbidity, pH and chemical behavior of dissolved solids) onrnthe ability of these metal ions and nanoparticles to disinfect drinking water.